(1) Field of the Invention
The present invention relates to a light-emitting semiconductor device.
(2) Description of the Related Art
Light-emitting diodes disclosed in, for example, Patent documents JP2000-182542 and U.S. Pat. No. 6,526,082 have a tunnel junction of GaN, and an anode placed in ohmic contact on the tunnel junction.
The tunnel junction enables light emission at a low voltage as well as formation of an anode and a cathode made of the same material. Therefore those electrodes can be efficiently manufactured. Electrodes mentioned in JP2000-182542 and capable of satisfactorily coming into ohmic contact with the GaN tunnel junction are made of AuGe/Ni.
In the light-emitting diode, the electrode is used as a reflecting surface to guide light in a light-emitting direction and to emit the light reflected by the electrode efficiently. Although light can be emitted at a high efficiency when the electrode has a higher reflectivity, the AuGe/Ni cannot form an electrode having a high reflectivity. Thus, the light-emitting diode provided with electrodes of AuGe/Ni cannot emit light at a high efficiency.